“The question is do we get divorced now or get divorced later,” she said Sunday night in their living room. “If I stand in the way of his dreams and passions, then we get divorced now, so I have to be supportive.”

Leaving behind a wife is difficult enough, but Ken Sullivan, 38, has four children ranging in age from 6 months to 13 years old.

“I don’t like it, not at all,” said Kaitlyn, 12, about the thought of her dad blasting off to Mars, never to return. “When he leaves, I’d have a way to talk to him, but I can’t ever see him in person again.”

Sullivan’s two oldest daughters, from a previous marriage, would be grown by the time the first mission takes off, currently set for 2024, but his 3-year-old son, Kaunner, and infant daughter, Tana, would be at ages where having a dad around is crucial.

“I just hope the family will be able to forgive me down the road,” he said. “Hopefully there isn’t too much hatred of my being selfish in pursuing a dream that isn’t theirs.”

His chances of making the final cut are slim, he realizes, but exploring another world is something that intrigued him enough to submit a video application and send it in before he even talked with his wife about it.

Sullivan says he loves his family more than Mars, but “my desire to explore and the opportunity to do something no one has ever done before, and making a name for myself, would be nice to do.”

The trip is one-way not only because there’s no feasible way to launch a ship from Mars, but also because a person’s bone density would decrease significantly under Martian gravity, which is a third as strong as Earth’s.

“There’s a point of no return for bone-density loss,” said Norbert Kraft, a medical doctor who is the Chief Medical Officer for Mars One.

The trip would take between six and seven months, and the initial crew would have only four people. If everything goes according to plan, four more people would go up every two years. The reason for the time gap, Kraft said, is that Earth and Mars need to be at their closest points to reduce travel time.